http://www.forbes.com/lifestyle/health/feeds/hscout/2005/12/01/hscout529360.html
Hormone Key to Keeping Weight Off
-- Robert Preidt
THURSDAY, Dec. 1 (HealthDay News) -- A new study offers insight into
why it's easier to lose weight than to keep it off for good.
Body weight is regulated by metabolic, neuroendocrine, and autonomic
systems, which work together to restore fat mass in people who've lost
weight, the study authors concluded. That's because the body interprets
reductions in weight as a deficiency in the hormone leptin.
These mechanisms explain why more than 85 percent of obese people
who've lost weight eventually regain those pounds, the Columbia
University researchers said.
They tested this theory by giving "replacement" doses of leptin to
obese people and to lean people who'd just lost weight. The leptin
doses reversed most of the metabolic, neuroendocrine and autonomic
changes that occur in an effort to counter reduced body weight.
The study appears in the Dec. 1 issue of the Journal of Clinical
Investigation.
The findings suggest that drugs that target the leptin signaling
pathway may help prevent people from regaining weight after they've
lost it, the scientists said.
A study published in November found that in obese rats, the receptor
for leptin -- which makes fat burn up -- disappears from fat cells.
This means that leptin can't act on the fat cells, the University of
Texas Southwestern Medical Center at Dallas researchers said.
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This is impossible. It says absolutely nothing about calories. Calories
are the only factor that influences weight gain and weight loss. This
goes against everthing we know about obesity and the laws of
thermodynamics.
TC